michael@0: /*
michael@0:  * Copyright 2006 The Android Open Source Project
michael@0:  *
michael@0:  * Use of this source code is governed by a BSD-style license that can be
michael@0:  * found in the LICENSE file.
michael@0:  */
michael@0: 
michael@0: #ifndef SkGradientShader_DEFINED
michael@0: #define SkGradientShader_DEFINED
michael@0: 
michael@0: #include "SkShader.h"
michael@0: 
michael@0: class SkUnitMapper;
michael@0: 
michael@0: /** \class SkGradientShader
michael@0: 
michael@0:     SkGradientShader hosts factories for creating subclasses of SkShader that
michael@0:     render linear and radial gradients.
michael@0: */
michael@0: class SK_API SkGradientShader {
michael@0: public:
michael@0:     enum Flags {
michael@0:         /** By default gradients will interpolate their colors in unpremul space
michael@0:          *  and then premultiply each of the results. By setting this flag, the
michael@0:          *  gradients will premultiply their colors first, and then interpolate
michael@0:          *  between them.
michael@0:          */
michael@0:         kInterpolateColorsInPremul_Flag = 1 << 0,
michael@0:     };
michael@0: 
michael@0:     /** Returns a shader that generates a linear gradient between the two
michael@0:         specified points.
michael@0:         <p />
michael@0:         CreateLinear returns a shader with a reference count of 1.
michael@0:         The caller should decrement the shader's reference count when done with the shader.
michael@0:         It is an error for count to be < 2.
michael@0:         @param  pts The start and end points for the gradient.
michael@0:         @param  colors  The array[count] of colors, to be distributed between the two points
michael@0:         @param  pos     May be NULL. array[count] of SkScalars, or NULL, of the relative position of
michael@0:                         each corresponding color in the colors array. If this is NULL,
michael@0:                         the the colors are distributed evenly between the start and end point.
michael@0:                         If this is not null, the values must begin with 0, end with 1.0, and
michael@0:                         intermediate values must be strictly increasing.
michael@0:         @param  count   Must be >=2. The number of colors (and pos if not NULL) entries.
michael@0:         @param  mode    The tiling mode
michael@0:         @param  mapper  May be NULL. Callback to modify the spread of the colors.
michael@0:     */
michael@0:     static SkShader* CreateLinear(const SkPoint pts[2],
michael@0:                                   const SkColor colors[], const SkScalar pos[], int count,
michael@0:                                   SkShader::TileMode mode,
michael@0:                                   SkUnitMapper* mapper = NULL,
michael@0:                                   uint32_t flags = 0);
michael@0: 
michael@0:     /** Returns a shader that generates a radial gradient given the center and radius.
michael@0:         <p />
michael@0:         CreateRadial returns a shader with a reference count of 1.
michael@0:         The caller should decrement the shader's reference count when done with the shader.
michael@0:         It is an error for colorCount to be < 2, or for radius to be <= 0.
michael@0:         @param  center  The center of the circle for this gradient
michael@0:         @param  radius  Must be positive. The radius of the circle for this gradient
michael@0:         @param  colors  The array[count] of colors, to be distributed between the center and edge of the circle
michael@0:         @param  pos     May be NULL. The array[count] of SkScalars, or NULL, of the relative position of
michael@0:                         each corresponding color in the colors array. If this is NULL,
michael@0:                         the the colors are distributed evenly between the center and edge of the circle.
michael@0:                         If this is not null, the values must begin with 0, end with 1.0, and
michael@0:                         intermediate values must be strictly increasing.
michael@0:         @param  count   Must be >= 2. The number of colors (and pos if not NULL) entries
michael@0:         @param  mode    The tiling mode
michael@0:         @param  mapper  May be NULL. Callback to modify the spread of the colors.
michael@0:     */
michael@0:     static SkShader* CreateRadial(const SkPoint& center, SkScalar radius,
michael@0:                                   const SkColor colors[], const SkScalar pos[], int count,
michael@0:                                   SkShader::TileMode mode,
michael@0:                                   SkUnitMapper* mapper = NULL,
michael@0:                                   uint32_t flags = 0);
michael@0: 
michael@0:     /** Returns a shader that generates a radial gradient given the start position, start radius, end position and end radius.
michael@0:         <p />
michael@0:         CreateTwoPointRadial returns a shader with a reference count of 1.
michael@0:         The caller should decrement the shader's reference count when done with the shader.
michael@0:         It is an error for colorCount to be < 2, for startRadius or endRadius to be < 0, or for
michael@0:         startRadius to be equal to endRadius.
michael@0:         @param  start   The center of the start circle for this gradient
michael@0:         @param  startRadius  Must be positive.  The radius of the start circle for this gradient.
michael@0:         @param  end     The center of the end circle for this gradient
michael@0:         @param  endRadius  Must be positive. The radius of the end circle for this gradient.
michael@0:         @param  colors  The array[count] of colors, to be distributed between the center and edge of the circle
michael@0:         @param  pos     May be NULL. The array[count] of SkScalars, or NULL, of the relative position of
michael@0:                         each corresponding color in the colors array. If this is NULL,
michael@0:                         the the colors are distributed evenly between the center and edge of the circle.
michael@0:                         If this is not null, the values must begin with 0, end with 1.0, and
michael@0:                         intermediate values must be strictly increasing.
michael@0:         @param  count   Must be >= 2. The number of colors (and pos if not NULL) entries
michael@0:         @param  mode    The tiling mode
michael@0:         @param  mapper  May be NULL. Callback to modify the spread of the colors.
michael@0:     */
michael@0:     static SkShader* CreateTwoPointRadial(const SkPoint& start,
michael@0:                                           SkScalar startRadius,
michael@0:                                           const SkPoint& end,
michael@0:                                           SkScalar endRadius,
michael@0:                                           const SkColor colors[],
michael@0:                                           const SkScalar pos[], int count,
michael@0:                                           SkShader::TileMode mode,
michael@0:                                           SkUnitMapper* mapper = NULL,
michael@0:                                           uint32_t flags = 0);
michael@0: 
michael@0:     /**
michael@0:      *  Returns a shader that generates a conical gradient given two circles, or
michael@0:      *  returns NULL if the inputs are invalid. The gradient interprets the
michael@0:      *  two circles according to the following HTML spec.
michael@0:      *  http://dev.w3.org/html5/2dcontext/#dom-context-2d-createradialgradient
michael@0:      */
michael@0:     static SkShader* CreateTwoPointConical(const SkPoint& start,
michael@0:                                            SkScalar startRadius,
michael@0:                                            const SkPoint& end,
michael@0:                                            SkScalar endRadius,
michael@0:                                            const SkColor colors[],
michael@0:                                            const SkScalar pos[], int count,
michael@0:                                            SkShader::TileMode mode,
michael@0:                                            SkUnitMapper* mapper = NULL,
michael@0:                                            uint32_t flags = 0);
michael@0: 
michael@0:     /** Returns a shader that generates a sweep gradient given a center.
michael@0:         <p />
michael@0:         CreateSweep returns a shader with a reference count of 1.
michael@0:         The caller should decrement the shader's reference count when done with the shader.
michael@0:         It is an error for colorCount to be < 2.
michael@0:         @param  cx      The X coordinate of the center of the sweep
michael@0:         @param  cx      The Y coordinate of the center of the sweep
michael@0:         @param  colors  The array[count] of colors, to be distributed around the center.
michael@0:         @param  pos     May be NULL. The array[count] of SkScalars, or NULL, of the relative position of
michael@0:                         each corresponding color in the colors array. If this is NULL,
michael@0:                         the the colors are distributed evenly between the center and edge of the circle.
michael@0:                         If this is not null, the values must begin with 0, end with 1.0, and
michael@0:                         intermediate values must be strictly increasing.
michael@0:         @param  count   Must be >= 2. The number of colors (and pos if not NULL) entries
michael@0:         @param  mapper  May be NULL. Callback to modify the spread of the colors.
michael@0:     */
michael@0:     static SkShader* CreateSweep(SkScalar cx, SkScalar cy,
michael@0:                                  const SkColor colors[], const SkScalar pos[],
michael@0:                                  int count, SkUnitMapper* mapper = NULL,
michael@0:                                  uint32_t flags = 0);
michael@0: 
michael@0:     SK_DECLARE_FLATTENABLE_REGISTRAR_GROUP()
michael@0: };
michael@0: 
michael@0: #endif